docstr: Calculate offsets to VDMX_Group records.
  For each ratRange return a list of offset values from the beginning of
  the VDMX table to a VDMX_Group.
docstr_tok: ["Calculate","offsets","to","VDMX_Group","records",".","For","each","ratRange","return","a","list","of","offset","values","from","the","beginning","of","the","VDMX","table","to","a","VDMX_Group","."]
code: def _getOffsets(self):
      """
      Calculate offsets to VDMX_Group records.
      For each ratRange return a list of offset values from the beginning of
      the VDMX table to a VDMX_Group.
      """
      lenHeader = sstruct.calcsize(VDMX_HeaderFmt)
      lenRatRange = sstruct.calcsize(VDMX_RatRangeFmt)
      lenOffset = struct.calcsize(">H")
      lenGroupHeader = sstruct.calcsize(VDMX_GroupFmt)
      lenVTable = sstruct.calcsize(VDMX_vTableFmt)
      # offset to the first group
      pos = (
          lenHeader
          + self.numRatios * lenRatRange
          + self.numRatios * lenOffset
      )
      groupOffsets = []
      for group in self.groups:
          groupOffsets.append(pos)
          lenGroup = lenGroupHeader + len(group) * lenVTable
          pos += lenGroup  # offset to next group
      offsets = []
      for ratio in self.ratRanges:
          groupIndex = ratio["groupIndex"]
          offsets.append(groupOffsets[groupIndex])
      return offsets
  
file_path: catboost/contrib/python/fonttools/fontTools/ttLib/tables/V_D_M_X_.py
imports: from .None import DefaultTable
  from fontTools.misc import sstruct
  from fontTools.misc.textTools import safeEval
  import struct
label_desc: Use image node_id 2 for calling the table_V_D_M_X_ obj's underlying member method code with example usage: obj._getOffsets() and returns: offsets